Automotive windshield wiper assembly designers have long recognized the need for a windshield wiper assembly which provides a nearly uniform load distribution across the wiper blade so that the blade conforms evenly to the windshield. In order to attain this uniform load distribution, the wiper arm is typically connected to a blade superstructure in which the wiper arm is attached to a central yoke, which is likewise attached to a pair of secondary yokes on either end, the secondary yokes then being attached along the length of the wiper blade. The yokes are typically pivotably attached to each other and to the wiper arm so that the wiper blade may flex when moving over an obstruction. In order to achieve that result, while also preventing obstruction of the yokes by accumulation of ice, snow, or other debris, owing in part to the design of the yokes, there must be a substantial distance between the central yoke and the secondary yokes to provide the required space for motion therebetween. Examples of such windshield wiper assemblies having high profile superstructures include U.S. Pat. No. 5,339,510 (Roth et al.), U.S. Pat. No. 5,048,145 (Takahashi et al.), U.S. Pat. No. 4,543,682 (Kessler et al.), U.S. Pat. No. 2,782,449 (Anderson), and French Patent 1,048,036 (Oishei). As shown in FIG. 5 herein, the superstructure of prior wiper blade constructions adds considerably to the height of the wiper assembly above a windshield.
Such high profile wiper blade constructions are undesirable on some windshield designs, particularly the "cab forward" windshield. The "cab forward" windshield design places the windshield at a lower angle from the horizontal, thus presenting a more aerodynamic profile and a more pleasing appearance. That design, however, potentially pushes the windshield wiper assembly more into the line of vision of a driver (FIG. 1).
Some windshield wiper assemblies have attached the wiper arm along side the wiper blade, as in U.S. Pat. No. 4,300,259 (Maiocco) and U.S. Pat. No. 1,684,477 (Demand). Such wipers do not, however, provide the uniform load distribution required to obtain satisfactory windshield wiping.
An additional problem with prior windshield wiper superstructures is the use of channeled yokes, which have a tendency to trap ice, now, and other debris between the three sides of the yoke comprising the channel, as seen in FIGS. 5, 8, and 9.
There is thus a need for a low profile windshield wiper assembly which provides a uniform load distribution across the wiper blade while not restricting motion of the yokes due to accumulated debris therebetween.